Lyphira chomel n. sp.

(Figs. 3E‒G, 6C, 7E, 9C, 10D, 11D, 12B, C, 13D, E, 14C, 15E, 16D, 17M‒R, 21C)

Lyphira heterograna . — Galil, 2009: 300 (part), figs. 12B, 14. (Not Philyra heterograna Ortmann, 1892)

Type material. Holotype: male (10.1 × 10.3 mm), ZRC 1999.0798, off Pontian, western Johor, Malaysia, coll. dredge, T.H.T. Tan & D. Vandenspiegel, 1992 . Paratypes: 1 ovigerous female (9.6 × 9.7 mm), ZRC 1985.0099, station Sig 3/11, on muddy substrate, off Bedok, Singapore, 16.5 m (9 fathoms), coll. dredge, D.S. Johnson, 1960s; 4 males (8.8 × 9.0 mm, 10.4 × 10.3 mm, 10.5 × 10.6 mm, 12.6 × 12.8 mm), 1 female (11.2 × 11.2 mm), 1 partially crushed female (13.5 × 13.4 mm), ZRC 1985.0091 – 0096, station B77, on mud, off Bedok, Singapore, 16.5 m (9 fathoms), coll. dredge, D.S. Johnson, 1960s ; 1 ovigerous female (11.4 × 11.1 mm) ZRC 1985.0098, station B78, mud substrate, off Tanjung Stapa, Pengerang, southeastern Johor, Peninsular Malaysia, 1°21'00.0"N 104°08'00.0"E, 31 m (17 fathoms), coll. dredge, D.S. Johnson, 1960s; 3 males (12.5 × 11.3 mm, 12.7 × 12.7 mm, 13.0 × 12.9 mm), 2 female (11.6 × 11.4 mm), NHM 1900.10.22.340–343, on mud, Malacca, Peninsular Malaysia, 1–2 m, coll. F. P. Bedford & W.F. Lanchester, 1899–1900.

Diagnosis. Carapace approximately as broad as long or slightly longer than broad, dorsal surface of carapace covered with closely spaced minute granules, hepatic and intestinal regions with larger, more prominent granules (Figs. 3E‒G, 6C). Frontal margin granulated, postfrontal lobe slightly convex (Figs. 11D, 13D, E). Endostomial spine absent (Figs. 13D, E, 14C). Lateral and posterolateral margin of carapace with row of small granules interspersed by larger granules; posterior carapace margin gently convex with row of larger granules (Figs. 3E‒F, 10D). Third maxilliped exopod 2.5 times as long as broad, slightly narrower than basal part of endopod, forming petaliform structure with convex outer margin, endopod with completely fused basis-ischium, longer than merus, with shallow submarginal sulcus near inner margin (Figs. 11D, 17M). Chelipeds subequal; merus covered by large rounded granules (Figs. 3E, 6C, 9C); surfaces of carpus and propodus covered by closely spaced small granules; chela slender, fingers longer than length of palm, surface with longitudinal sulcus flanked by row of granules; pollex slightly bent, cutting edge lined with denticles, large tooth subproximally; dactylus 1.5 times as long as palm along upper margin, row of small granules on upper margin, cutting edge with median large tooth lined with denticles, remaining of edge with small denticles (Fig. 15E). P2–P5 slender, long; merus distinctly longer than carpus and propodus; dactylus longer than propodus, lanceolate, terminating in corneous tips (Figs. 3E); fourth leg shortest with merus 5.6 times as long as broad, margins almost smooth, lined barely with small granules (Fig. 16D). Thoracic sternites transversely narrow, surface granulated, larger granules laterally (Fig. 7E). Sternopleonal cavity deep, reaching to proximal distance between fused thoracic sternites 1–3. Pleon narrow, somites 2–6 fused, somite 6 longitudinally subrectangular, surface with one low granule subdistally, lateral margins gently convex; telson triangular (Figs. 7E, 17N). G1 elongate, slender, same size from proximal to distal area; distal process gently curved, with blunt tip (Fig. 17O‒R). Female pleon broad, convex, smooth, somites 2‒6 fused, suture between somites 2 and 3; telson as long as its basal width (Fig. 9C); vulvae positioned closer to median part of sternite 6, each opening relatively broad, ovate, without opercular cover (Fig. 21C).

Colour. Not known.

Etymology. The named is derived from the Malay word for small and cute, “chomel ”. The name is used as a Latin noun in apposition.

Remarks. Lyphira chomel n. sp. is a very distinct species. Its short and poorly developed endostomial spines, and the relatively narrow third maxilliped exopod allies it with L. heterograna s. str. and L. acutidens, but L. chomel n. sp. can immediately be distinguished by its prominently slenderer and elongate ambulatory meri (Fig. 16D) and the granules on the merus of the cheliped being evenly spread out, reaching to the distal surfaces (Fig. 3E). In L. heterograna s. str. and L. acutidens, the ambulatory meri are distinctly shorter and stouter (Fig. 16A‒C) and the distal surfaces of the merus of the cheliped are relatively smoother with only scattered granules present (Fig. 3A‒D). The G1s of L. chomel n. sp. and L. heterograna s. str., however, are similar, with the apical process longer and gently curved (Fig. 17C‒F, O‒R). On the basis of published data, L. chomel n. sp. is also the smallest species, with male specimens as small as 10 mm in carapace width already mature and females of a similar size already ovigerous. Lyphira heterograna s. str. and L. acutidens both reach larger sizes (smallest adult female averages 12 mm carapace width) (cf. Chen 1987; Chen & Sun 2002; present data).

Galil’s (2009: 300) stated she examined several specimens of “ L. heterograna ” from Peninsular Malaysia: four males and two females from Malacca (NHM 1900.10.22.340–345) and one male from Pontian (ZRC 1999.0798). Galil (2009: figs. 12B, 14) figured a male specimen (15.1 mm carapace length, NHM 1900.10.22.340–345) (incorrectly stated as from Indonesia). Her figures agree very well with the holotype male of L. chomel n. sp. (which is here based on her Pontian male), including the pattern of granules on the merus of the cheliped, relatively slenderer P2–P5 and structure of the G1.

In Singapore, L. chomel n. sp. is sympatric with L. linda n. sp., but they appear to have slightly different habitats. Although both are intertidal to subtidal, L. chomel n. sp. appears to prefer more muddy substrates, whereas L. linda n. sp. likes area which are sandier.

Type locality. Pontian, Peninsular Malaysia .

Distribution. Southern Peninsular Malaysia and Singapore.